Hydroisomerization of motor fuel stocks

ABSTRACT

A method of obtaining an improved octane rating by hydroisomerization which involves separating a stock into two portions, individually hydroisomerizing the portions for olefin conversion and combining the two hydroisomerized streams.

United states Patent Lewis G. Larson Bartlesville, Okla.

Sept. 19, 1969 Nov. 9, 1971 Phillips Petroleum Company inventor Appl. No. Filed Patented Assignee l-IYDROISOMERIZATION OF MOTOR FUEL STOCKS 5 Claims, No Drawings US. Cl 208/80, 208/57, 208/138, 260/683.65, 260/683.67 Int. Cl C07c 5/24, ClOg 39/00 Field of Search 208/79, 80,

I l37l38; 260/683.65, 683.67

Primary ExaminerDelbert E. Gantz Assistant Examiner-G. E. Schmitkons An0rneyYoung and Quigg ABSTRACT: A method of obtaining an improved octane rating by hydroisomerization which involves separating a stock into two portions, individually hydroisomerizing the portions for olefin conversion and combining the two hydroisomerized streams.

HYDROISOMERIZATION F MOTOR FUEL STOCKS This invention relates to motor fuel production.

In one of its more specific aspects, this invention relates to hydroisomerization of stocks in the motor fuel range for the purpose of quality improvement.

Catalytically cracked and pyrolysis gasolines normally contain olefins and diolefins which have a deleterious effect on the gasoline inasmuch as they tend to form gums.'Such materials are particularly prevalent in certain deisopentanized stocks, derived from the cracking, having an initial boiling point of about 100 F. and anend point of about 400 F. While the total stock can be hydroisomerized for olefin, acetylene, and diolefin conversion to other forms of hydrocarbons, it has now been determined that improved results are realized if this raw gasoline is divided into two portions, each of which is individually hydroisomerized, the two portions being recombined thereafter to provide a motor gasoline blending stock. The method of this invention provides such a process.

According to the method o this invention there is provided a process for hydroisomerizing a cracked gasoline containing olefins which comprises separating the stock into two portions of different boiling ranges, hydroisomerizing each portion individually over different hydroisomerization catalysts and combining the hydroisomerized streams to produce a gasoline blending stock having a higher octane number than can be produced by hydroisomerizing the total stock over either of the catalysts. The method of this invention, in one of its aspects, contemplates treating cracked gasoline obtained by cracking a stream comprising substantially virgin gas oil over a cracking catalyst such as silica-alumina, molecular sieve, etc. in a fluid catalytic cracking unit. This product stream will comprise C s through about 400 F. end point material, and will have an olefin content of about 55 percent and a diolefin-acetylene content of about 1 percent. A g if 7 7W The catalytically cracked gasoline-to be isomerized is divided into two portions. The first portion is a 200 F. end point material and comprising olefinic materials. The second portion is a 2000 F.400 F. El. cut comprising substantially aromatics and some small amount of olefins. Both portions contain diolefins.

Accordingly, it is an object of this invention to provide an improved method of hydroisomerizing olefins present in cracked gasolines.

It is another object of this invention to provide an improved motor fuel blending stock.

This invention can be carried out in any of the usual processing sequences, including series or parallel flow of the individual reactants. Catalysts suitable for promoting the reactions involved are the conventional palladium on alumina-type catalysts and the nickel sulfide-type catalysts.

Palladium on alumina catalysts can be employed in any convenient form, such as pelleted or spherical shapes. The catalysts will contain about 0.005 to about 1.0 weight percent palladium on alumina, preferably about 0.01 to about 0.1 percent. The alumina will be of controlled pore diameter and will contain about 41.5 weight percent alumina. It will weigh about 40-52 pounds per cubic foot, will have a surface area of about 340-350 square meters per gram, a pore volume ofabout 0.50 to 0.60 milliliters per gram, and a pore diameter of about 60 to about 70 A. While this catalyst will be spoken of herein as the palladium catalyst, it is to be understood that equally suitable catalysts include the noble metals of. Group VIII of the Periodic Table of Elements, Handbook of Chemistry and Physics, Chemical Rubber Company, 45th Edition (1964), page 8-2, and include ruthenium, rhodium palladium, osmium, iridium and platinum on such supports as alumina, silicaalumina, glass beads and carbon.

The second catalyst employed in the method of this invention will be referred to herein as the nickel sulfide catalyst. It will comprise a solid acid isomerization catalyst containing a sulfide of one or more of the metals of the left-hand column of Group Vl including chromium, molybdenum, tungsten and/or a sulfide of one or more of the metals of Group VIII, for example, iron, cobalt, nickeL of the Periodic Table. Such catalysts contain the metal sulfide in the range of about 0.5 to about 15 percent by weight based upon the total catalyst, the support being any suitable support such as silica, alumina, etc. Both the catalysts employed herein are well known and their preparation and use is described in the prior art.

This invention contemplates the separation of the cracked product into two individual stocks which are individually hydroisomerized. .Any suitable method of separating the cracked stock into the individual stocks is satisfactory, fractionation being preferably employed to produce a first stock, the 200 F. end point stock having an end point of from about 200250 F., and a second stock, the "400 F. end point stock having an IB? of from about200-250 F. and an end point of about 375-450 F.

The-200 F. end point stock is contacted with a palladium catalyst in a catalytic contacting zone in substantially the vapor phase to hydrogenate the diolefins and to isomerize the olefins to internal olefins. Generally the reaction is conducted at a temperature of about 200300 F., at a pressure of about 10 to 200 p.s.i.g., in the presence off hydrogen in an amount of from about 2 to about 10 mols of hydrogen per mol of diolefins plus acetylenes, at a liquid space velocity, vol./vol./hr., of from about 1 to about 4.

The 400 F. end point stock is contacted in a catalytic contacting zone with the sulfide catalyst in substantially the vapor phase at a temperature of about 400-750" F .,-at a pressure of about 200-1000 p.s;i.g. in the presence of hydrogen in an amount from about 2 to about 10 mols of hydrogen per mol of I hydrocarbon, at a liquid space velocity, vol./vol./hr., of about The individually isomerized stocks are combined to produce a motor fuel blending stock.

The practice of the method of this invention produces a motor fuel blending stock having a higher octane member than is obtainable when treating the unproportioned cracked stock, as-such, with either of the catalysts under comparable conditions. This is indicated by the following runs in which a catalytically cracked gasoline containing C through 400 F. end point material, having an olefin content of about 55 volume percent, a diolefin-acetylene content of about 1 percent, and a research octane number, with 3 cc. of tetraethyllead per gallon, of 97.0 was treated in its entiretywith the two catalysts concerned under the following conditions.

'Hydrogcn/Diolefins plus Acctylenes Mol Ratio is 5:!

In contrast to this method and in accordance with the method of this invention, the same stock was fractionated to produce a C -200 F. end point material which was isomerized with a palladium catalyst in accordance with -the procedure described-below,'and 200-400 F. out which was treated with the nickel sulfide catalyst under the conditions indicated below. The octane number indicated is on the stream after the treated portions were recombined in their entirety.

Stock Conditions C,-'200 F. End point 200-400 F. End Point Catalyst Palladium-alumina Nickel Sulfide Temperature, F. 250 600 Pressure, p.s.i.g. 50 500 Hydrogen/Diolcfins plus Acetylenes Mol Ratio is it will be seen from the above data that the resulting blend of the two individually isomerized streams has an octane number greater than that of the product produced by treating the total stock with either of the catalysts concerned.

it will be appreciated that normal variations can be employed in the carrying out of the process. For example, the hydrogen can be introduced at a plurality of points into the reaction zone; a plurality of catalyst beds can be employed, the various beds having different operating temperatures; the generous stream containing the hydrogen can be composed of various percentages of hydrogen and can include inert materials.

Other modifications of a related nature will be evident. However, such modifications are considered to be within the scope of the invention.

What is claimed is:

l. A method of hydroisomerizing a cracked gasoline containing olefins, diolefins and aromatics and having a boiling range from about C through about 400 F. to produce a product having an improved octane number which comprises:

a. separating said cracked gasoline into a first portion and a second portion, said first portion having an end point within the range of about 200-250 F. comprising olefins and diolefins, said second portion having an initial boiling point within range of about 200-250 F. and an end point within the range of 375-450 F. and comprising a minor amount of olefins and a substantial amount of aromatics;

b. a hydroisomerizing said first portion by contacting said first portion with hydrogen and a catalyst consisting essentially of a supported noble metal of Group VIII of the Periodic Table to hydrogenate said diolefins and to isomerize said olefins to internal olefins and to produce a first hydroisomerized stream;

c. hydroisomerizing said second portion by contacting said second portion with hydrogen and a catalyst consisting essentially of a supported sulfide of a metal of the lefthand column of Group VI of the Periodic Table to produce a second hydroisomerized stream;

d. combining said first hydroisomerized stream and said second hydroisomerized stream; and,

e. recovering the combined stream as said produce.

2. The method of claim 1 in which said cracked gasoline has an olefin content of about 55 percent and a diolefin-acetylene content of about lpercent.

3. The method of claim 1 which said first portion is hydroisomerized by contact with a catalyst consisting essentially of supported palladium and said second portion is hydroisomerized by contact with a catalyst consisting essentially of supported nickel sulfide.

4. The method of claim 1 in which said first portion is hydroisomerized in the vapor phase at a temperature within the range of about 200-300 F. at a pressure of about 10 to 200 p.s.i.g. and a said second portion is hydroisomerized in the vapor phase at a temperature in the range of about 400-750 F. at a pressure of about 200-1 000 p.s.i.g.

5. The method of claim 3 in which said first portion is hydroisomerized at a temperature of about 250 F. at a pressure of about 50 p.s.i.g., at a space velocity of about 2 and at a hydrogen to hydrocarbon mol ratio of about 0.05 and said second portion is hydroisomerized at a temperature of about 600F. at a pressure of about 500 p.s.i.g., at a space velocity of about 1 and at a hydrogen to hydrocarbon mol ratio of about 6.

UNITED STATES PATEJT OFFICE CERTIFICATE OF CORRECTION Date November 9, 1971 Patent No. 3,619, 08

Lewis G. Larson It is certified that error appears in the above-identified patent and that 5.1; Letters Patent are hereby corrected as shown below:

Column h, line 2, delete the word "a"; line 15, the word "produce" should reac product Signed and sealed this 11th day of April 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR. Atte sting Officer Commissioner of Patents 

2. The method of claim 1 in which said cracked gasoline has an olefin content of about 55 percent and a diolefin-acetylene content of about 1percent.
 3. The method of claim 1 which said first portion is hydroisomerized by contact with a catalyst consisting essentially of supported palladium and said second portion is hydroisomerized by contact with a catalyst consisting essentially of supported nickel sulfide.
 4. The method of claim 1 in which said first portion is hydroisomerized in the vapor phase at a temperature within the range of about 200-300* F. at a pressure of about 10 to 200 p.s.i.g. and a said second portion is hydroisomerized in the vapor phase at a temperature in the range of about 400-750* F. at a pressure of about 200-1000 p.s.i.g.
 5. The method of claim 3 in which said first portion is hydroisomerized at a temperature of about 250* F. at a pressure of about 50 p.s.i.g., at a space velocity of about 2 and at a hydrogen to hydrocarbon mol ratio of about 0.05 and said second portion is hydroisomerized at a temperature of about 600*F. at a pressure of about 500 p.s.i.g., at a space velocity of about 1 and at a hydrogen to hydrocarbon mol ratio of about
 6. 